Annular knife for a surgical stapler

ABSTRACT

A surgical stapling device includes a handle assembly, a central body extending distally from the handle assembly, and a head portion including an anvil assembly and a shell assembly. The shell assembly includes an annular knife having an inner surface and an outer surface and first and second angled surfaces defining a blade edge. The first angled surface defines an angle S 1  with a longitudinal axis of the stapling device and the second angled surface defines an angle S 2  with the longitudinal axis of the stapling device.

BACKGROUND 1. Technical Field

The present disclosure relates to surgical staplers, and more particularly, to circular surgical staplers including annular knives.

2. Background of Related Art

Anastomosis is the surgical joining of separate hollow organ sections. In known circular anastomosis procedures, two ends of organ sections are joined by means of a stapling device which drives a circular array of staples through each organ section and simultaneously cores any tissue interior of the driven circular array of staples to free a tubular passage. Examples of such devices are described in U.S. Pat. Nos. 7,234,624, 6,945,444, 6,053,390, 5,568,579, 5,119,983, 4,646,745, 4,576,167, and 4,473,077, the contents of which are all incorporated herein by reference in its entirety.

Typically the circular stapling device has an elongated shaft having a handle portion at a proximal end and a staple cartridge at a distal end. An anvil assembly including an anvil rod with an attached anvil head is mounted to the distal end of the device. The anvil is approximated to clamp tissue between a staple holding component of the staple cartridge and an anvil plate of the anvil assembly. The clamped tissue is stapled by actuation of the handle portion to drive circular arrays of staples through the tissue. Concurrently, an annular knife is advanced by actuation of the handle portion to core tissue inboard of a staple array.

It would be advantageous to provide an annular knife with improved manufacturability, blade strength, and cutting performance.

SUMMARY

The present disclosure provides in one aspect a surgical stapler having a handle assembly, a central body extending distally from the handle assembly, and a head portion including an anvil assembly and a shell assembly. The shell assembly includes an annular knife having an inner surface and an outer surface. The knife includes first and second angled surfaces defining a blade edge, wherein the first angled surface defines an angle S1 with a longitudinal axis of the shell assembly and the second angled surface defines an angle S2 with the longitudinal axis.

In some embodiments, the blade edge is radially offset from the outer surface of the knife a distance of between 0.0001 to 0.0003 inches.

In certain embodiments, the second angled surface defines an inner beveled surface of the knife and the first angled surface defines an outer beveled surface of the knife.

In embodiments, the angle S1 is greater than the angle S2.

In some embodiments, the angle S1 is equal to the angle S2.

In certain embodiments, the angle S1 is less than the angle S2.

In embodiments, the angle S1 is between 15 degrees and 50 degrees and the angle S2 is between 3 degrees and 15 degrees.

In some embodiments, the angle S1 is 30 degrees and the angle S2 is 8 degrees.

In embodiments, a portion of the knife is coated with a lubricant.

In some embodiments, the shell assembly further includes a housing, a pusher back and a staple guide supporting a plurality of staples, the pusher back being movable relative to the staple guide to eject staples from the staple guide.

In certain embodiments, the pusher back defines a central throughbore and the knife is secured within the central throughbore of the pusher back.

The present disclosure provides in another aspect a shell assembly for a surgical stapler having a housing, a pusher back, and a staple guide supporting a plurality of staples, wherein the pusher back is movable relative to the staple guide to reject staples from the staple guide.

In embodiments, the shell assembly further includes an annular knife having an inner surface and an outer surface, the knife including a first and second angled surfaces defining a blade edge, wherein the first angled surface defines an angle S1 with a longitudinal axis of the shell assembly and the second angled surface defines an angle S2 with the longitudinal axis of the shell assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed surgical stapler are described herein below with reference to the drawings, wherein:

FIG. 1 is a perspective view of a first embodiment of the presently disclosed surgical stapler of the present disclosure;

FIG. 2 is a cross-sectional view taken along section line 2-2 of FIG. 1;

FIG. 3 is an enlarged view of the area of detail of FIG. 2;

FIG. 4 is a side, perspective view of the knife of the stapler of FIG. 1;

FIG. 5 is a cross-sectional view taken along section line 5-5 of FIG. 4; and

FIG. 6 is an enlarged view of the area of detail of FIG. 5.

DETAILED DESCRIPTION OF EMBODIMENTS

The presently disclosed surgical stapler will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. Throughout this description, the term “proximal” will refer to the portion of the stapler closer to the operator and the term “distal” will refer to the portion of the stapler further from the operator.

The presently disclosed stapler is particularly suited for surgical procedures for the treatment of colon prolapse and hemorrhoids, although it can be used for other procedures. According to the present disclosure, the surgical stapler includes an annular knife having a blade edge where the blade edge is defined by a double beveled knife geometry. It is contemplated that a double beveled knife geometry provides improved manufacturability, blade strength, and cutting performance.

FIG. 1 illustrates one embodiment of the presently disclosed surgical stapler 10. Briefly, surgical stapler 10 includes a handle assembly 12, a central body or elongated portion 14 and a distal head portion or end effector 16. Head portion 16 includes an anvil assembly 18 and a shell assembly 20.

Except where otherwise noted, the components of stapler 10 are generally formed from thermoplastics including polycarbonates, and metals including stainless steel and aluminum. The particular material selected to form a particular component will depend upon the strength requirements of the particular component. For example, the anvil may be formed from a metal such as stainless steel, whereas portions of handle assembly 12 may be formed from thermoplastic such as a polycarbonate. Alternately, other materials having the requisite strength requirements which are suitable for surgical use may be used to form the components of surgical stapler 10.

Handle assembly 12 includes a stationary handle 22, a firing trigger 24, an approximation knob 26, an indicator assembly 28, and a lockout mechanism 30. The approximation knob 26 functions to retract and advance a drive screw (not shown) to advance or retract the anvil assembly 18 in relation to the shell assembly 20. The firing trigger 24 functions to actuate a pusher (not shown) to eject staples from shell assembly 20.

Each of the components of handle assembly 12 identified above are substantially as described in U.S. Pat. No. 7,303,106 (“'106 patent”) entitled “Surgical Stapling Device With Visual Indicator” which issued on Dec. 4, 2007. The '106 patent is incorporated herein by reference in its entirety. Accordingly, these components and assemblies will not be described in further detail herein.

Referring to FIGS. 2 and 3, the anvil assembly 18 includes an anvil shaft or center rod 32 and an anvil head 34. The anvil shaft 32 includes a tapered proximal blunt end (not shown) and an opposite distal end 33 for mounting the anvil head 34. In embodiments, the anvil head 34 is fixedly mounted to the distal end 33 of anvil shaft 32. Alternatively, the anvil head 34 may be pivotally mounted to the distal end 33 of anvil shaft 32 such that the anvil head 34 can move between an operative non-tilted position to a tilted position (not shown). This is described in detail in the '106 patent.

In embodiments, the anvil shaft 32 includes a series of cut-outs 36 forming cinch spots to provide a purse-string attachment location. Each of the cut-outs 36 is configured to receive a purse-string suture to allow a clinician to fixedly secure the purse-string suture to a desired portion of the anvil shaft 32. The series of cut-outs 36 enables the clinician to control the amount of tissue that is drawn into the shaft assembly 20 during approximation of the anvil assembly 18 and thus, to control the amount of tissue to be cut by a knife 42 as described below. This is described in detail in U.S. Pat. No. 8,408,441 (“the '441 patent), the contents of which are incorporated herein by reference in their entirety. Alternatively, it is envisioned that an anvil shaft may be provided that does not define cut-outs.

The shell assembly 20 is secured to the distal end of central body portion 14 of the surgical stapler 10 and includes a shell or housing 38, a pusher back 40, the knife 42, and a staple guide 44 housing one or more rows of staples 46. The pusher back 40 defines a central throughbore 48 which is slidably positioned about an inner guide portion 50 of the shell 38 and includes a plurality of fingers 52. Each of the fingers 52 is dimensioned to be slidably received within slots 54 formed in the staple guide 44 to eject the staples 46 from the staple guide 44.

With reference to FIGS. 4-6 in conjunction with FIGS. 2 and 3, the knife 42 is retained within the central throughbore 48 of the pusher back 40. In embodiments, the knife 42 is fixedly secured within pusher back 40 using, for example, adhesives, crimping, pins, or friction. Alternatively, other techniques can also be used to secure the knife 42 within the pusher back 40.

As shown in FIG. 4, the knife 42 is annular and includes an inner surface 56 a and an outer surface 56 b. The distance between the inner surface 56 a and the outer surface 56 b defines a blade thickness “T,” wherein “T” is from about ______ to about ______. [Please provide ranges for blade thickness.] The knife 42 also includes a distal blade edge 60 that is defined by the intersection of an inner beveled surface 58 a and an outer beveled surface 58 b formed at the distal end of the knife 42 as described in further detail below.

As discussed above, the inner beveled surface 58 a and the outer beveled surface 58 b intersect to define the blade edge 60. In embodiments, the blade edge 60 is offset from the outer surface 56 b of the knife 42 in a radial direction a distance “D” (see FIG. 6). In embodiments, the distance “D” is approximately 0.0001 to 0.0003 inches. Alternatively, the distance “D” may be selected to position the blade edge 60 at a desired distance from the outer surface 56 b of the knife 42. In embodiments, the blade edge 60 can be positioned close to the outer surface 56 b. By positioning the blade edge 60 closer to the outer surface 56 b of the knife 42, a greater amount of tissue can be cored from within shell 30 during advancement of the knife 42. In alternative embodiments, it is envisioned that the blade edge 60 may sit closer to or further from the inner surface 56 a of knife 42.

The inner beveled surface 58 a of knife 42 defines an angle “S1” with a longitudinal axis of the shell 30 and the outer beveled surface 58 b defines an angle “S2” with the longitudinal axis of the shell 30. In embodiments, the angle “S1” of inner beveled surface 58 a may range from about 15 degrees to about 50 degrees and the angle “S2” of the outer beveled surface 58 b may range from about 3 degrees to about 15 degrees. For example, in embodiments, the angle “S1” may be about 30 degrees and the angle “S2” may be about 8 degrees. Alternatively, the angle “S1” of the inner beveled surface 58 a may be less than the angle “S2” of the outer beveled surface 58 b. The specific angles of the angle “S1” and the angle “S2” may vary depending on the purpose of the knife 42 and the desired location of the blade edge 60.

It is contemplated that a double beveled knife geometry, such as, for example, the asymmetrical knife blade geometry in FIGS. 2-6, may decrease the manufacturing cost of knife 42. For example, it is contemplated that manufacturing the knife 42 having double beveled surfaces may reduce the amount of burr on a given beveled surface. As such, the manufacturing process would not require a de-burring step.

It is also contemplated that an asymmetrical double beveled knife may achieve better cut performance and retraction performance than known stapler knives.

As disclosed above, components of the stapler 10 may be fabricated from suitable metals such as stainless steel or aluminum. Accordingly, in embodiments, knife 42 may be fabricated from a stainless steel, such as, for example, 420J2 stainless steel. Alternatively, the knife 42 may be fabricated from any suitable material.

In embodiments, a portion of the inner and/or outer surface 56 a, 56 b of the knife 42 may be coated with a material to enhance its lubricity. Such a coating may allow the knife 42 to more easily pass through tissue and prevent the knife 42 from sticking to materials with which the knife 42 comes into contact, such as, for example, tissue (not shown). For example, in embodiments, the knife 42 may be coated with silicon to increase its penetration, cut, and retraction performance. Such a coating is described in detail in U.S. Pat. No. 7,942,302, entitled “Surgical Stapling Device With Coated Knife Blade,” which issued on May 17, 2011, the entire contents of which are incorporated herein by reference.

Stapler 10 is particularly suitable for use in surgical procedures for treating colon prolapse. During such procedure, an access port is inserted into the anus to facilitate access to a prolapsed colon. Next, a purse string suture (not shown) is placed into, above or in the vicinity of the colon prolapse and the anvil assembly 18 is inserted through the access port into the anus and rectum. Thereafter, a purse string suture (not shown) is secured to the anvil shaft 32, e.g., one of the cut-outs 36 of the anvil shaft 32.

The cut-outs 36 are longitudinally spaced along the shaft 32 such that the amount of tissue drawn into the shell assembly 20 can be controlled by securing the purse string suture to a selected one of the cut-outs 36. A greater amount of tissue is drawn into the shell assembly 20 by securing the purse string suture to the proximal-most cut-out 36. Likewise, a lesser amount of tissue is drawn into the shell assembly 20 by securing the purse string suture to the distal-most cut-out 36. The purse string suture is tightened to pull tissue towards the anvil shaft 32.

The surgeon can then visualize the tissue to be stapled, i.e. the tissue donut to be removed. The stapling instrument, e.g. instrument 10 of FIG. 1, is inserted through the port and attached to the anvil assembly 18, with the elongated anvil shaft 32 and elongated instrument shaft providing increased visibility. The anvil assembly 18 and the shell assembly 20 are then approximated via the knob 26 to draw a portion of the tissue defining the prolapsed colon into the shell assembly 20.

When the surgical stapler 10 is fully approximated, the firing trigger 24 can be actuated or fired in a manner described in the '106 patent to staple and sever (using the knife 42) the portion of the prolapsed colon. Thereafter, the stapler 10 is at least partially unapproximated and removed from the anus with the excised tissue contained within a receptacle (not shown) of the pusher back 40 within the shell assembly 20. In the embodiments where the anvil assembly 18 includes a tilting anvil head 34, the anvil head 34 is unapproximated from the shell assembly 20 to allow the anvil head 34 to tilt (not shown) to its inoperative position to facilitate removal of the anvil assembly 18 from within the anus.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. An surgical stapler comprising: a handle assembly; a central body extending distally from the handle assembly; and a head portion including an anvil assembly and a shell assembly, wherein the shell assembly includes an annular knife having an inner surface and an outer surface, the knife including first and second angled surfaces defining a blade edge, wherein the first angled surface defines an angle S1 with a longitudinal axis of the shell assembly and the second angled surface defines an angle S2 with the longitudinal axis of the shell assembly.
 2. The surgical stapler of claim 1, wherein the knife has a thickness T of between 0.011 and 0.013, and the blade edge is radially offset from the outer surface of the knife a distance of between 0.0001 to 0.0003 inches.
 3. The surgical stapler of claim 1, wherein the second angled surface defines an inner beveled surface of the knife and the first angled surface defines an outer beveled surface of the knife.
 4. The surgical stapler of claim 1, wherein the angle Si is greater than the angle S2.
 5. The surgical stapler of claim 1, wherein the angle S1 is equal to the angle S2.
 6. The surgical stapler of claim 1, wherein the angle S1 is less than the angle S2.
 7. The surgical stapler of claim 1, wherein the angle S1 is between 15 degrees and 50 degrees and the angle S2 is between 3 degrees and 15 degrees.
 8. The surgical stapler of claim 7, wherein the angle S1 is 30 degrees and the angle S2 is 8 degrees.
 9. The surgical stapler of claim 1, wherein a portion of the knife is coated with a lubricant.
 10. The surgical stapler of claim 10, wherein the lubricant is silicon.
 11. The surgical stapler of claim 1, wherein the shell assembly further includes a housing, a pusher back and a staple guide supporting a plurality of staples, the pusher back being movable relative to the staple guide to eject staples from the staple guide.
 12. The surgical stapler of claim 12, wherein the pusher back defines a central throughbore and the annular knife is secured within the central throughbore of the pusher back.
 13. A shell assembly for a surgical stapler comprising: a housing; a pusher back; a staple guide supporting a plurality of staples, wherein the pusher back is movable relative to the staple guide to eject staples from the staple guide; and an annular knife having an inner surface and an outer surface, the knife including a first and second angled surfaces defining a blade edge, wherein the first angled surface defines an angle S1 with a longitudinal axis of the shell assembly and the second angled surface defines an angle S2 with the longitudinal axis of the shell assembly.
 14. The shell assembly of claim 15, wherein the pusher back defines a central throughbore and the knife is secured within the central throughbore of the pusher back.
 15. The shell assembly of claim 15, wherein the blade edge is radially offset from the outer surface of the knife a distance of between 0.0001 to 0.0003 inches.
 16. The shell assembly of claim 15, wherein the second angled surface defines an inner beveled surface of the knife and the first angled surface defines an outer beveled surface of the knife.
 17. The shell assembly of claim 15, wherein the angle S1 is greater than the angle S2.
 18. The shell assembly of claim 15, wherein the angle S1 is less than the angle S2. 